Device with jaws for locking/unlocking a lid on a vessel

ABSTRACT

A device for locking/unlocking a lid (1) on a vessel (2) to form a pressure cooking vessel. The device has at least two radially movable jaws (15a, 15b) on the lid (1), a portion (50) for controlling the movement of the jaws (15a, 15b), actuating members (20a, 20b) connected to each of the jaws (15a, 15b) and provided with at least one locking aperture (25a, 25b, 250), and at least one locking valve (10) mounted on the lid (1) and movable into a raised position in which it engages the aperture(s) (25a, 25b, 250) and locks the jaws (15a, 15b). The device is characterized in that it comprises a locking valve (10) combined with two actuating arms (20a, 20b) positionable one above the other at least when the jaws are in the locking position, the actuating arms having respective locking apertures (25a, 25b) arranged to be in register in the locking position.

TECHNICAL FIELD

The present invention relates to the general technical field oflocking/unlocking devices for a cover of a container to form a cookingvessel, preferably of the pressure type.

The present invention concerns a locking/unlocking device for a cover ofa cooking vessel, preferably under pressure, comprising at least twojaws mounted to be radially movable in opposition to one another on thecover between a locking position of the cover and an unlocking positionas well as a means for controlling the movement of the jaws in a mannerto cause them to assure one or the other of the fixed positions oflocking or unlocking.

PRIOR ART

There is already known, according to patent application WO-92/03083 apressure cooking vessel using a locking/unlocking device composed ofjaws which are mounted for radial movement on the cover. The jaws, ofwhich there are two, are diametrically opposite one another relative tothe longitudinal axis of the vessel and are adapted such that when intheir closing position they tightly grip the peripheral edge of thecontainer in order to hermetically seal the vessel. Conversely, the jawscan occupy an unlocking position permitting opening of the vessel.Control of the displacement of the jaws is assured by a control means,which is a button mounted to move axially on the cover in a centralposition. The control means is provided with engagement surfaces whichare specially shaped to act, during displacement of the control button,on inclined surfaces fixed to the jaws in order to displace themradially. Such a control system thus transforms, in a conventionalmanner, an axial movement into a radial displacement movement of thejaws between a closing position and an opening position.

It can be considered that such a device represents a positivecontribution to systems for locking vessels in a closed position forpressure cooking, particularly because it does not require a relativelyprecise positioning such as indexing, between the cover and thecontainer. On the other hand, such a system has been found to require aseries of pieces which are movable relative to one another, and inparticular radially, to assure control of disengagement of the jaws. Thearrangements proposed imply combinations of complex movements, such astranslations and rotations, provoking risks of significant jamming andleading to high fabrication costs and a less than optimum operatingreliability.

It is equally in order to note that the control mechanism of theabove-described device, as well as the relative displacements of thevarious parts, requires a relatively substantial physical effort on thepart of the user.

Moreover, the prior art device does not comprise a system which permitsassuring that the jaws are in a perfect locking position, orconsequently of detecting that the vessel is correctly closed. It can ineffect occur that for reasons of partial blockage or of defectivedisplacement of the jaws or of the pieces assuring their movement, thejaws only assure a partial locking of the cover on the container. Itbeing a matter of a vessel under pressure, detection of a complete andcorrect closing of the jaws is thus of a major importance for the safetyof the user.

SUMMARY OF THE INVENTION

The object of the present invention is in consequence to provide aremedy to the various difficulties enumerated previously, and to providea new locking/unlocking device for a pressure vessel permittingassurance in a simple and reliable manner of the good position of thejaws and of the complete and certain closing of the cover on thecontainer.

Another object of the invention is to furnish a new locking/unlockingdevice in which the displacement of the jaws is particularly facilitatedwhile being robust and simple.

Another object of the invention is to provide a new locking/unlockingdevice whose overall rigidity and assembly are improved.

Another object of the invention is to provide a novel locking/unlockingdevice in which the jaws are permanently brought into the lockingposition.

The objects assigned to the invention are achieved with the aid of alocking/unlocking device for a cover on a container in order to form apressure cooking vessel comprising:

at least two jaws mounted to be radially movable in opposition on thecover, between a locking position of the cover on the container and anunlocking position,

a means for controlling movement of the jaws in a manner to cause themto assure one or the other of their locking or unlocking position,

drive elements connected to each jaw, formed by drive arms fixed to atleast each jaw, one of the arms being provided with a locking aperture,

at least one locking valve mounted on the cover and adapted to occupyunder the effect of the pressure existing in the vessel a raisedposition and a lowered position, the valve or valves and the aperture orapertures being disposed relatively so that in the locking position ofthe jaws, the valve or valves can engage the aperture or apertures inthe raised position to lock the jaws in locking position characterizedin that it comprises a locking valve associated with two drive arms,capable of being superimposed at least in the locking position of thejaws and each comprising a locking aperture disposed to coincide in thelocking position.

BRIEF DESCRIPTION OF THE DRAWINGS

Other particularities and advantages of the invention will appear andbecome more readily apparent from a reading of the description presentedhere below, with reference to the attached drawings, given by way ofillustrative and nonlimiting examples in which:

FIG. 1 shows, in a general transverse cross sectional view, the upperportion of a cooking vessel provided with a locking/unlocking deviceaccording to the invention.

FIG. 2 shows, in a top plan view, a cooking vessel provided with thelocking/unlocking device according to the invention, in which the jawsare in the locking position.

FIG. 3 shows, in a top view identical to that of FIG. 2, the jaws of thelocking/unlocking device according to the invention in the unlockingposition.

FIG. 4 shows, in a partial enlarged cross sectional view, a constructiondetail of the locking/unlocking device according to the invention in thelocking position.

FIG. 5 shows, in a view analogous to that of FIG. 4, a partial crosssectional view of the locking/unlocking device according to theinvention in the unlocking position.

FIG. 6 shows, in a partial cross sectional view, a detail of the controlmeans of the device according to the invention.

FIGS. 7 and 8 show alternative embodiments of the invention.

BEST MODE OF PRACTICING THE INVENTION

The locking/unlocking device according to the invention is intended toassure closing by locking of a cover 1 on a container 2 in a manner toform a cooking vessel, preferably one for cooking under pressure such asa pressure cooker. The vessel is, for example, constituted by acontainer of substantially cylindrical form, with an axis of revolutionx-x', on which cover 1 is intended to be connected in a sealed manner,for example by the intermediary of a lip-type seal 3. Container 2 is, ina conventional manner, made of a metallic material such as stainlesssteel and is provided with a thermally conductive bottom that is fixedto container 2, for example by hot stamping. The container 2 alsoincludes gripping elements such as handles 5 fixed to the walls ofcontainer 2 by the intermediary of attachment feet 6 and screws 7.

Cover 1 includes a profiled closing disk 8 provided at its peripherywith a zone in the form of a groove 9 serving as a reception seat forlip-type seal 3, and assuming therewith the fluid tightness of theclosing of cover 1.

Closing disk 8 is provided with at least one opening 10a permitting thepassage and assembly of a locking valve 10 mounted for free axialsliding in said opening between a lower abutment position (such as shownin FIG. 5 for example), and an upper abutment position (such as shown inFIG. 4). Locking valve 10 can be constituted in a manner well known inthe prior art of a safety finger whose principal purpose is to furnish avisual indication of the pressure existing in the vessel under pressure.Advantageously, the steam tightness, between the locking valve 10 andthe opening 10a is improved by the interposition of a seal 11, thislatter being maintained in position by resting on a flange 12 formingthe lower radially exterior part of the locking valve 10.

Cover 1 also includes at least two jaws 15a, 15b, mounted radiallymovably on the closing disk 8 between a locking position of the cover 1on the container 2 (FIGS. 2 and 4) and an unlocking position (FIGS. 3and 5). Jaws 15a, 15b have, in a conventional manner, U-shaped crosssections in the form of segments adapted to the shape of the vessel, andin the embodiment illustrated in the drawings, in the form of circulararcs having a selected length. Each jaw 15 includes a lower edge 16 andan upper edge 17, permitting each jaw to grip, respectively, theperipheral edge 2a of container 2 and the upper limit of groove 9. Eachjaw 15a, 15b is movably mounted on the cover by the intermediary ofdrive elements including associated drive arms 20a, 20b, diametricallyopposite and fixed by an extremity 21, for example by soldering orwelding, to the upper edge 17. In the preferred embodiment of theinvention shown in FIGS. 1-5, each drive arm 20a, 20b has the form of aprofiled metal piece, which may be generally straight or flat, having ashape adapted to that of closing disk 8 and a transverse cross sectionin the form of a U which opens toward the exterior of the vessel andwhose sides 22 also extend toward the exterior of the vessel.

According to a preferred embodiment of the invention, drive arms 20a,20b have a length sufficient to be able to overlap, at least in part,during their radial displacement. Drive arms 20a, 20b are in particularcapable of overlapping at least in the locking position of the jaws.According to this embodiment, drive arms 20a, 20b are advantageouslyself guided radially by one another, arm 20a forming the male arm and20b forming the female arm, the male arm sliding in the female arm.Relative guiding of arms 20a, 20b is obtained by cooperation andfriction of sides 22 of each of arms 20a, 20b . Such an arrangementobviously permits a reduction in the risks of possible deformationduring radial sliding of each of the arms 20a, 20b, and allows a perfectmastery of linear displacement of each jaw 15a, 15b.

According to this preferred embodiment of the invention, each drive arm20a, 20b is provided with a locking aperture 25a, 25b extending acrossthe central part of each arm. The location of each locking aperture 25a,25b is determined as a function of the length of each arm 20a, 20b suchthat apertures 25a, 25b would be in an alignment position when each jaws15a, 15b are in locking position. Simultaneously, the position ofapertures 25a, 25b, as well as the position of opening 10a and thus alsovalve 10, is selected so that when jaws 15a, 15b are in the lockingposition, apertures 25a, 25b as well as opening 10a are aligned. Thisarrangement permits locking valve 10 to occupy the predeterminedposition corresponding to the pressure existing within the vessel, andin particular to occupy its upper abutment position (FIG. 4) in whichvalve 10 engages in each locking aperture 25a, 25b to lock the jaws intheir locking position. Such a position is obviously only achieved whenjaws 15a, 15b occupy their locking position precisely, because only thencan valve 10 move simultaneously through apertures 25a, 25b . In thecase where the alignment of apertures 25a, 25b is not achieved during anattempted operation, valve 10 can not be displaced upwardly, with theresult that there will be a sufficient escape of steam out of the vesselto prevent any pressure rise within the vessel.

Advantageously, guiding of linear and radial movement of drive arms 20a,20b is assured by supplemental guide means which are fixed to cover 1.

According to a preferred embodiment of the invention, the guide meansare formed by a support piece 30 which embraces arms 20a, 20b along themajor part of their length.

According to a preferred embodiment of the invention, support piece 30is formed from a plate having a transverse cross section in the form ofa U, embracing and covering drive arms 20a, 20b, the U being oriented toface closing disk 8. Support plate 30 is advantageously fixed to closingdisk 8 by the intermediary of two anchoring points 31 and 32, situatedat opposite sides of the longitudinal axis of support plate 30.Anchoring points 31, 32 can be constituted by suitable fixing means,such as screws, or can also serve as the location for the passage ofpressure regulation means. By way of a modification, it is equallypossible to mount support plate 30 in a reversed manner, the internalface of support plate 30 being turned toward the exterior of the vessel,the arms 20a, 20b sliding in one another as well as in the supportplate. In this position, support plate 30 embraces and supports arms20a, 20b.

According to another variant of the invention, the guide means can beconstituted by ramps or equivalent means, fixed to or integral withclosing disk 8.

In all cases, and in particular in the case where a support plate 30,presenting a U-shaped profiled, is utilized, the guide means assume, inaddition to a function of supplementary aid to the linear sliding of thearms 20a, 20b, a complementary function of rigidifying the mechanicalassembly, assuring radial displacement of jaws 15a, 15b.

The path of displacement of drive arms 20a, 20b, between each of theirlimit positions, corresponding to the opening and closing position ofjaws 15a, 15b, is limited by the intermediary of a slot 40, preferablyarranged in male arm 20a, in which can be displaced a lug 41 fixed tothe female arm 20b . The path of displacement of arms 20a, 20b is thuslimited by the establishment of abutment positions of lug 41 against oneor the other of the two extremities of slot 40. According to aparticular embodiment, support plate 30 comprises an opening alignedwith apertures 25a, 25b, as well as with opening 10a, permitting theassembly in suspension of locking valve 10 (FIG. 5), by its upper partof reduced cross section relative to the lower part of the locking valve10. Such an arrangement permits relative sliding of drive arms 20a, 20bwhen valve 10 is in its lower position, which simultaneously assuresfree movement of jaws 15a, 15b.

Advantageously, drive arms 20a, 20b are brought permanently in thelocking position by an elastic return means constituted for example by atension spring 45 interposed between two hooks which are respectivelyfixed to each of drive arms 20a, 20b.

The locking/unlocking device according to the invention also comprises acontrol means 50 for the movement of jaws 15a, 15b, permitting each jawto be brought into one or the other of their fixed locking/unlockingposition.

According to a preferred embodiment of the invention such as shown inFIGS. 4 and 6, control means 50 has the form of an element for grippingcover 1 and is constituted by a control element 56 mounted for movementin a substantially radial direction on cover 1 and coupled kinematicallywith a control button 52 mounted on cover 1 to be movable in asubstantially axial direction.

Control means 50 is constituted by a knob 51 which is fixed to cover 1,and by control button 52 mounted to be axially and elastically movableby a return spring 52a in knob 52. Return spring 52a maintains controlbutton 52 in the upper position shown in FIGS. 4 and 6. Control button52 comprises at its lower part an activation finger 53 provided with aninclined engagement surface 54 intended to come to engage, duringdepression of control button 52, a complementary engagement surface 55arranged on control element 56. Control element 56 is mounted on cover 1according to a predetermined path in a manner to be brought, during itsdisplacement between two limits defining its path, to engage drive arms20a, 20b in a manner to control their radial displacement.

According to a preferred embodiment of the invention, control element 56assures radial displacement of drive arms 20a, 20b in an active mannerin the radial external direction, i.e. in a direction corresponding tothe progressive spreading apart of jaws 15a, 15b, to attain theirextreme unlocking position. According to this preferred embodiment ofthe invention, control element 56 is coupled kinematically with controlbutton 52 whose displacement in the substantially axial directiondefined previously controls the displacement of drive arms 20a, 20b inthe radially inward direction, i.e. in a direction of displacement ofthe jaws in the direction of their locking position. For this purpose,control element 56 is formed by a button mounted on knob 51. Button 56presents a control zone 57 which is raised and manually accessible tothe user, as well as a flat activating triangular zone 58 arranged toengage with activating means fixed to drive arms 20a, 20b . According toa preferred embodiment of the invention, the activating means areconstituted by the lug 41 and by a corresponding lug 41b which is fixedto drive arm 20b . Displacement of the triangular zone 58 in a radialdirection, in either sense thus permits displacement equally radially oflugs 41, 41b but in a direction which is oriented at 90° with respect tothe direction of displacement of button 56. By the expedient of thetriangular zone 58, button 56 consequently engages in an active mannerdrive arms 20a, 20b to progressively assure their spreading apart whenthe user presses on the control zone 57. When the guide means are formedby a support plate 30 covering drive arms 20a, 20b, the support plate 30comprises two openings 40a, 40b, arranged in the central part of saidplate, and intended for the passage, respectively, of lugs 41, 41b, topermit their radial displacement. Openings 40a, 40b have for theirsecondary function to limit the individual displacement path of each arm20a, 20b by serving as an abutment for lugs 41, 41b, thus preventingdisengagement of jaws 15a, 15b outside of cover 1.

Advantageously, triangular activating zone 58 comprises two recesses60a, 60b, for example semicircular and in any case of a formcomplementary to that of lugs 41, 41b, in a manner to determine a stableand fixed opening position for the jaws corresponding to a blockage inposition of said lugs in the corresponding recesses 60.

During depression of control button 52, the activating finger 53, whenthe jaws 15a, 15b are in the unlocking position, comes to engage thecomplementary engaging surface 55 in order to control the release ofbutton 56. The release corresponds to movement of lugs 41, 41b out ofrecesses 60a, 60b, activating finger 53 thus forming release means whilerecesses 60 form blocking means.

According to the preferred embodiment of the invention shown in FIGS. 1to 4, control element 56 and control button 52 are mounted on the coverin a central position in order to form a lifting assembly for the cover.

By way of a variation, it is of course possible to separate the liftingassembly of the cover from the control element 56 and the control button52.

By way of a complementary modification, it is obviously also possible,without departing from the framework of the invention, to provide acontrol device comprising a single control element 56 capable ofassuring, by itself, control in the two senses of radial displacement ofthe drive arms 20a, 20b . According to this modification, controlelement 56 assures displacement of drive arms 20a, 20b in an activemanner in the radially external direction and in the radially internaldirection defined previously. Control element 56 is then constituted bya simple push button whose shape permits the user by a simple pushing orpulling to assure spreading or moving together of jaws 15a, 15b.

Cover 1 can include a trim plate 65 covering the totality of themechanism, said plate being placed in a sandwich between support plate30 and knob 51.

The functioning of the locking of the locking/unlocking device accordingto the invention is the following.

Placement of cover 1 on container 2 requires opening of jaws 15a, 15band radial activation of button 56 which permits a sliding movement oftriangular activating zone 58 which comes to progressively engage by itsflanks the lugs 41, 41b (FIG. 2). The progressive displacement of button56 permits progressive moving apart of the drive elements and inparticular the drive arms 20a, 20b, and simultaneously the jaws 15a, 15b. The translation of button 56 in a radial direction thus permits thetranslation of the two jaws 15a, 15b . The end of the translation isdetermined by the positioning of each lug 41, 41b in the associatedrecesses 60a, 60b (FIG. 3). Beyond this translation, the limit positionof jaws 15a, 15b is equally determined by the abutment position of lug41 against the extremity of slot 40. In the position thus attained, thejaws 15a, 15b are in a stable unlocking position and thus permit acentering of cover 1 on the edge of container 2 (FIG. 5).

Closing of the receptacle, i.e. the attainment by jaws 15a, 15b of theirlocking position, is obtained by pressure of the palm of the hand on thebutton of knob 52 which is consequently activated axially. Its downwardmovement in the knob 51 provokes the engagement of engagement surface 54against its complementary surface 55 arranged on push button 56, whichis progressively pushed back in a radially external direction. Duringthe course of this translation in the inverse sense, lugs 41, 41b arefirst of all freed from recesses 60a, 60b, the jaws 15a, 15b then beingprogressively pulled toward one another toward their locking position(FIGS. 2 and 4). The return toward this locking position is obtained bythe return action of spring 45 permitting the positioning of each jaw15a, 15b between the cover 1 and under the edge 2a of the container 2.

The vessel thus being closed in a sealed manner, pressure can thereafterincrease and provoke the passage of locking valve 10 into its upperposition through apertures 25a, 25b, which in the complete closingposition of jaws 15a, 15b, are coaxial. The engagement of locking valve10 through apertures 25a, 25b (FIG. 4) permits locking in position ofeach of the drive arms 20a, 20b, and simultaneously each correspondingjaw.

The locking/unlocking device according to the invention thus permits toassure an increase in pressure in complete safety since passage of thelocking valve into the apertures 25a, 25b can only occur if the drivearms 20a, 20b, and thus the jaws 15a, 15b are in perfect lockingposition. The locking valve 10 opposes, moreover, any radialdisplacement of jaws 15a, 15b . The radial and linear displacement ofthe drive arms 20a, 20b, is moreover obtained without risk ofdeformation due to the presence of a succession of guide means formed bythe sliding of the interior arms in one another and by the support plate30.

As an example of a complementary variation, it is obviously possible toresort to drive arms 20a, 20b which are not mounted relatively one withrespect to the other in an overlapping position, the locking beingobtained with the aid of a locking valve 10 associated with each of thedrive arms 20a, 20b.

According to another embodiment (FIG. 7), the drive elements are formedby each actuating member (drive arm) 20a, 20b which is extended at theopposed end of the jaw 15a, 15b by two links 25'a, 25'b mounted movablyin rotation on the associated arm by a same axis. The pairs of links25'a, 25'b are articulated between one another in order to form adeformable parallelogram, connected to the control means 50. The jaws15a, 15b are pulled toward one another in an elastic manner by a spring45. The retraction or extension of the parallelogram controls the radialdisplacement of jaws 15a, 15b . According to this embodiment, it ispossible to provide only a single locking valve 10 associated with asingle locking aperture 250, formed on a drive element for example onone of the drive arms 20a, 20b, and/or equally in one of the links ofeach pair 25'a, 25'b. Each link can nevertheless comprise a lockingaperture 250 and be associated with a locking valve 10. As in the otherembodiments, the locking apertures 250 can also be arranged in thecentral part of each arm 20a, 20b, which can also be superposed at leastin part in the locking position.

According to another embodiment, shown in FIG. 8, the drive elements areformed by drive arms 20a, 20b, connected by the intermediary ofactivating bars 250a, 250b for example bent, to a central common bar260, mounted to be movable in rotation on the cover, preferably alongthe axis of rotation Ox of the receptacle. The central bar 260 isconnected to the control means 50, in a fashion to be able to be rotatedin the direction of arrows f1, f2, around the axis Ox in order tocontrol the radial displacement f3, f4 of the drive arms 20a, 20b. Tothis end the activating bars 250a, 250b which extend each associateddrive arm 20a, 20b, slide in respective apertures 261a, 261b, formingsliders arranged in each extremity of the central bar 260. According tothis embodiment, the drive arms 20a, 20b ar equally susceptible to besuperposed at least in part in the locking position.

POSSIBILITIES OF INDUSTRIAL APPLICATION

The invention finds its industrial application in the fabrication ofvessels for cooking under pressure, in particular pressure cookers.

We claim:
 1. Locking/unlocking device for a cover (1) on a container (2)to form a pressure cooking vessel comprising:at least two jaws (15a,15b) radially movably mounted in opposition on the cover (1), between alocking position of the cover (1) on the container (2) and an unlockingposition, a means for control (50) of the movement of the jaws (15a,15b) in a manner to cause them to assure one or the other of theirlocking or unlocking position, drive elements (20a, 20b) connected toeach jaw (15a, 15b), formed by drive arms fixed to each jaw (15a, 15b)at least, one of the arms (20a, 20b) being provided with a lockingaperture (25a, 25b, 250), at least one locking valve (10) mounted on thecover (1) and adapted to occupy under the effect of pressure existing inthe vessel, an upper position and a lower position, the valve or valves(10) and the aperture or apertures (25a, 25b, 250) being disposedrelatively so that in the locking position of the jaws (15a, 15b), thevalve or valves (10), can engage the aperture or apertures (25a, 25b,250) in the upper position to lock the jaws (15a, 15b) in the lockingposition characterized in that it comprises one locking valve (10)associated with two drive arms (20a, 20b) capable of being superimposedat least in the locking position of the jaws and each comprising alocking aperture (25a, 25b) disposed to coincide in the lockingposition.
 2. Device according to claim 1 characterized in that the drivearms (20a, 20b) are guided radially, for example self guided one in theother by sliding.
 3. Device according to claim 1 characterized in thatthe drive arms (20a, 20b) are provided at each of their extremity withone pair of links (25'a, 25'b) movable and articulated between them toform a deformable parallelogram connected to the means for control (50).4. Device according to claim 3 characterized in that it comprises asingle locking aperture (250) arranged in one of the links.
 5. Deviceaccording to claim 1 characterized in that the drive arms (20a, 20b) areconnected together by a central bar (260), mounted to be movable inrotation on the cover (1), and connected to the means for control (50).6. Device according to claim 5 characterized in that the central bar(260) is movable in rotation along the axis of revolution (Ox) of thevessel and is provided with two orifices (261a, 261b) forming slides inwhich slide the activation bars (250a, 250b) extending each of the drivearms (20a, 20b) when the central bar (260) is placed in rotation inorder to control the radial displacement of the drive arms (20a, 20b).7. Device according to claim 1 characterized in that it comprises meansfor guiding the radial movement of the drive arms (20a, 20b), said meansbeing fixed to the cover (1).
 8. Device according to claim 7characterized in that the means for guiding are formed by a supportpiece (30) holding the drive arms (20a, 20b).
 9. Device according toclaim 8 characterized in that the support piece (30) covers the drivearms (20a, 20b).
 10. Device according to claim 8 characterized in thatthe means for guiding are formed by a plate having a transverse sectionin the form of a U, holding and supporting the drive arms (20a, 20b).11. Device according to claim 1 characterized in that the drive arms(20a, 20b) are formed of a female arm (20b) and a male arm (20a) whichslides in the female arm, the relative path of the arms being limited bythe intermediary of a slot (40) arranged in one arm, preferably in themale arm (20a), and in which can be displaced between two abutmentpositions, corresponding to the fixed positions of locking andunlocking, a lug (41) fixed to the other arm, preferably the female arm(20b).
 12. Device according to claim 11 characterized in that therelative path of the drive arms is limited by two openings (40a, 40b)arranged in the support plate (30) and intended for the passagerespectively of lug (41) and of a lug (41b) fixed to the female arm(20b).
 13. Device according to claim 1 characterized in that the drivearms (20a, 20b) are brought permanently into the locking position by anelastic restoring means (45).
 14. Device according to claim 13characterized in that the elastic restoring means (45) is a springinterposed between each of the drive arms (20a, 20b).
 15. Deviceaccording to claim 1 comprising a device for controlling the opening andthe closing of the jaws (15a, 15b) characterized in that it comprises acontrol element (56) mounted for movement in a substantially radialdirection on the cover (1) and along a determined path, said element(56) being led, during its displacement, to engage the drive arms (20a,20b) in a fashion to control their radial displacement.
 16. Deviceaccording to claim 15 characterized in that the control element (56)assures the displacement of the drive arms in an active manner in theradial external sense and in the radial internal sense.
 17. Deviceaccording to claim 15 characterized in that the control element (56)assures the displacement of the drive arms in an active manner in theradial external sense, said control element (56) being coupledkinematically with a control button (52) mounted to be movable on thecover (1) in a substantially axial direction adapted to control thedisplacement of the drive arms (20a, 20b) in the radially internalsense.
 18. Device according to claim 17 characterized in that thecontrol element (56) comprises means for blocking (60) the drive arms(20a, 20b) in the unlocking position, the control button (52) comprisingrelease means (53, 54) to control the disarming of the means forblocking (60).
 19. Device according to claim 15 characterized in thatthe control element is a push button (56) adapted to be controlledmanually.
 20. Device according to claim 19 characterized in that thepush button (56) actively engages the drive arms (20a, 20b) by theintermediary of a triangular zone (58) to assure the spreading of thedrive arms (20a, 20b).
 21. Device according to claim 20 characterized inthat the means for blocking (60) are formed by recesses (60) arranged inthe triangular zone (58) to cooperate with the lugs (41, 41b) fixed tothe drive arms (20a, 20b).
 22. Device according to claim 17characterized in that the control button (52) is movable axially in anactive manner by depression.
 23. Device according to claim 18characterized in that the release means (53, 54) comprise an activatingfinger (53) adapted to engage the push button (56) during axialdepression of the control button (52).
 24. Device according to claim 17characterized in that control element (56) and the control button (52)are mounted on the cover (1) in a central position to form a holdingassembly.